Easy-to-disassemble strong and weak adhesives and preparation methods thereof

Abstract

The application provides a strong-weak adhesive and a preparation method thereof, relates to the technical field of strong-weak adhesive preparation, and discloses a strong-weak adhesive which comprises, from top to bottom, a strong adhesive layer with a thickness of 30-40 microns, a base material layer, and a weak adhesive layer with a thickness of 15-25 microns. The strong-weak adhesive can fix a component to be fixed on a base body, and when maintenance is needed, the component can be completely and cleanly detached from the base body without damaging the surface of the component and the base body.

Description

Technical Field

[0001] This invention relates to the field of strong and weak adhesive preparation technology, specifically to an easily disassembled strong and weak adhesive and its preparation method. Background Technology

[0002] In the manufacturing process of electronic devices such as computers and smartphones, it is often necessary to fix internal components such as camera modules, flexible printed circuit boards (FPCs), and batteries to the shell, mid-frame, and other housings. Currently, the industry mainly uses mechanical fixing or adhesive fixing methods.

[0003] While mechanical fastening facilitates disassembly and maintenance, it occupies valuable internal space, hindering the development of thinner and lighter devices, and also presents problems such as stress concentration and structural complexity. Therefore, adhesive fastening, due to its advantages such as flexible design, uniform stress distribution, and its contribution to achieving thinner and waterproof designs, has been widely used in electronic equipment assembly.

[0004] However, existing adhesive bonding technologies present significant technical contradictions: On the one hand, to ensure the reliability of components during use, adhesives must possess high bonding strength to resist stress caused by drops, vibrations, and changes in temperature and humidity, achieving permanent fixation. However, once cured, these adhesives are extremely difficult to remove, and forced removal often leads to irreversible damage to the bonded components or housing. On the other hand, to meet the needs of electronic device repair, component recycling, or upgrades, the adhesive connection must be easily disassembled. While some pull-out adhesive products exist that achieve disassembly by stretching the adhesive layer in a specific direction to thin it and reduce its stickiness, these typically require reserved space for stretching, making them unsuitable for the extremely limited space of camera miniature modules. Furthermore, there are solutions using removable adhesives, but their bonding strength is generally low, failing to meet the requirements of applications demanding high fixation strength.

[0005] Therefore, existing technologies struggle to balance the conflicting requirements of high-strength permanent fixation and on-demand, non-destructive disassembly. In particular, there is a lack of adhesive solutions that can firmly secure the component to the substrate while allowing for clean and complete removal from the substrate without damaging the component or substrate surface. To address this, the present invention provides an easily disassembleable strong / weak adhesive, aiming to solve the aforementioned technical problems. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an easy-to-disassemble strong and weak adhesive and its preparation method.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides an easy-to-disassemble strong and weak adhesive, which comprises, from top to bottom, a strong adhesive layer with a thickness of 30-40μm, a substrate layer, and a weak adhesive layer with a thickness of 15-25μm.

[0009] Secondly, the present invention provides a method for preparing the easily disassembled strong and weak adhesive, comprising weighing and mixing the components of the strong adhesive layer according to the mass ratio to obtain a strong adhesive layer adhesive, weighing and mixing the components of the weak adhesive layer according to the mass ratio to obtain a weak adhesive layer adhesive, applying the strong adhesive layer adhesive to the surface of a release material, drying it, and then attaching it to one side of a substrate, applying the weak adhesive layer adhesive to the surface of the release material, drying it, and then attaching it to the other side of the substrate to obtain the easily disassembled strong and weak adhesive.

[0010] Compared with existing technologies, it has the following beneficial effects:

[0011] This invention provides an easily removable strong-weak adhesive, comprising, from top to bottom, a strong adhesive layer with a thickness of 30-40 μm, a substrate layer, and a weak adhesive layer with a thickness of 15-25 μm. The strong adhesive layer has high bonding strength, adhering firmly to the shell to form a strong, permanent bond, providing a stable and reliable foundation for the micro-module, resisting external forces such as drops and vibrations, and meeting the reliability requirements of the device. The weak adhesive layer has moderate adhesion, firmly fixing the micro-module and ensuring it does not loosen during normal use. Furthermore, when the micro-module needs to be disassembled, it can be cleanly and completely peeled off without damaging the module or the adhesive tape, achieving non-destructive disassembly. The substrate layer prevents excessive deformation of the adhesive tape when peeling off the weak adhesive layer, ensuring that the weak adhesive layer is completely removed.

[0012] In the weak adhesive layer component of the present invention, the total amount of crosslinking agent A and crosslinking agent B is 0.8-1.2 parts, and the mass ratio of crosslinking agent A to crosslinking agent B is (1-3):1. The prepared weak adhesive layer of the tape can achieve a balance in terms of interfacial adhesion, heat resistance of the adhesive, and no adhesive residue. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the structure of the easily removable strong and weak adhesive PET tape prepared in Example 1.

[0015] Among them, 1-strong adhesive layer, 2-substrate layer, and 3-weak adhesive layer. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] This application provides an easy-to-disassemble strong and weak adhesive and its preparation method, which solves the technical problem in the prior art that it is difficult to achieve both high-strength permanent fixation and on-demand non-destructive disassembly. It achieves the effect of being able to firmly fix the component to be fixed to the substrate, and when disassembly is required, it can be cleanly and completely removed from the substrate without damaging the component and the surface of the substrate.

[0018] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0019] Based on this, the first aspect of the present invention provides an easy-to-disassemble strong and weak adhesive, which includes, from top to bottom, a strong adhesive layer with a thickness of 30-40μm, a substrate layer, and a weak adhesive layer with a thickness of 15-25μm.

[0020] The aforementioned adhesive layer of the strong and weak adhesive is highly adhesive and bonded to the shell to form a strong and permanent bond, providing a stable and reliable fixing foundation for the micro-module. It can resist external forces such as drops and vibrations, meeting the reliability requirements of the equipment. The weak adhesive layer has moderate adhesion force, which can firmly fix the micro-module and ensure that the micro-module does not loosen during normal use. When the micro-module needs to be disassembled, it can be cleanly and completely peeled off without damaging the module and the tape, achieving non-destructive disassembly. When peeling off the weak adhesive layer, the substrate layer can prevent the tape from being excessively deformed, ensuring that the weak adhesive layer is completely torn off.

[0021] In some embodiments, the strong adhesive layer comprises the following components in parts by weight: 100 parts acrylic pressure-sensitive adhesive, 0.8-1.0 parts crosslinking agent, 3.0-10.0 parts tackifying resin, and 5.0-7.0 parts solvent. Under these conditions, the adhesive has high bonding strength, adheres firmly to the shell, forming a strong and permanent bond, providing a stable and reliable fixing foundation for the micro-module, and resisting external forces such as drops and vibrations, thus meeting the reliability requirements of the equipment.

[0022] In some embodiments, the crosslinking agent is selected from isocyanate or epoxy crosslinking agents.

[0023] In some embodiments, the tackifying resin is selected from rosin esters or terpene resins.

[0024] In some embodiments, the solvent is selected from at least one of toluene, ethyl acetate, and butanone.

[0025] In some embodiments, the substrate layer is selected from polyethylene terephthalate (PET), polyethylene (PE) foam substrate, and thermoplastic polyurethane elastomer (TPU). This substrate layer prevents excessive deformation of the tape during the peeling of the weak adhesive layer, ensuring that the weak adhesive layer is completely removed.

[0026] In some embodiments, the weak adhesive layer comprises the following components in parts by weight: 100 parts of portable acrylic pressure-sensitive adhesive, crosslinking agent A, crosslinking agent B, and 10-12 parts of solvent. Under these component conditions, the adhesive has moderate adhesion, firmly securing the micro-module and ensuring it does not loosen during normal use. Furthermore, when the micro-module needs to be disassembled, it can be cleanly and completely peeled off without damaging the module or the tape, achieving non-destructive disassembly.

[0027] As a preferred embodiment, crosslinking agent A is an aziridine-type crosslinking agent, and crosslinking agent B is an isocyanate-based crosslinking agent. The total amount of crosslinking agent A and crosslinking agent B is 0.8-1.2 parts, for example, 0.8 parts, 1.0 parts, 1.2 parts, or any value between them. The mass ratio of crosslinking agent A to crosslinking agent B is 1-3:1, for example, 1:1, 2:1, 3:1, or any value between them.

[0028] In this invention, the mass ratio of aziridine crosslinking agent to isocyanate crosslinking agent in the weak adhesive layer component is very important. In the weak adhesive layer component of this invention, the aziridine crosslinking agent reacts with the carboxyl groups (-COOH) on the movable acrylic pressure-sensitive adhesive polymer chain to form dense anchor points, thereby enhancing the cohesive force of the weak adhesive layer. The isocyanate crosslinking agent reacts with the hydroxyl groups (-OH) on the movable acrylic pressure-sensitive adhesive polymer chain to construct a tougher long-chain structure, significantly improving the peel strength and heat resistance of the weak adhesive layer. The mass ratio of aziridine crosslinking agent to isocyanate crosslinking agent has a significant impact on the residual amount, interfacial adhesion, and heat resistance of the weak adhesive layer. Specifically, when the content of aziridine crosslinking agent is higher, it can improve the cohesion of the weak adhesive layer and effectively prevent stringing and residue during peeling. However, the interfacial adhesion and heat resistance will decrease. Therefore, in order to balance the interfacial adhesion of the weak adhesive layer, the heat resistance of the adhesive, and the residue-free performance, the preferred total amount of aziridine crosslinking agent and isocyanate crosslinking agent is 0.8-1.2 parts, and the mass ratio of aziridine crosslinking agent to isocyanate crosslinking agent is (1-3):1.

[0029] Secondly, the present invention provides a method for preparing the easily disassembled strong and weak adhesive, comprising weighing and mixing the components of the strong adhesive layer according to the mass ratio to obtain a strong adhesive layer adhesive, weighing and mixing the components of the weak adhesive layer according to the mass ratio to obtain a weak adhesive layer adhesive, applying the strong adhesive layer adhesive to the surface of a release material, drying it, and then attaching it to one side of a substrate, applying the weak adhesive layer adhesive to the surface of the release material, drying it, and then attaching it to the other side of the substrate to obtain the easily disassembled strong and weak adhesive.

[0030] Taking the bonding of a laptop camera module to the B-shell frame as an example, the specific bonding process using easily removable strong and weak adhesive tape is as follows:

[0031] 1. Die-cut tape

[0032] Cut the adhesive tape of varying strengths and widths into 5mm-20mm widths, and then die-cut the tape according to the shape of the camera module to ensure that the bonding area is covered and the edges are neat.

[0033] 2. Bonding process

[0034] Clean the surfaces: Clean the bonding surfaces of the B-shell frame and camera module to ensure they are free of oil and dust.

[0035] Peel off the release paper: Peel off the release paper from the strong adhesive layer side, stick the tape to the designated position on the B-frame, and apply pressure to ensure a firm bond.

[0036] Fixing the camera: Align the camera module with the position and press it onto the weak adhesive layer side, which provides a fixing effect.

[0037] 3. Disassembly process

[0038] When it is necessary to disassemble the camera, insert a plastic disassembly tool into the gap between the camera module and the B-shell frame, and apply pulling force to easily separate the weak adhesive layer without leaving any adhesive residue. After the weak adhesive layer is separated, the strong adhesive layer remains bonded to the B-shell frame, and disassembly is completed by slowly peeling it off, leaving no adhesive residue.

[0039] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0040] I. Preparation Method

[0041] Example 1

[0042] This embodiment provides an easily removable PET strong and weak adhesive tape, which, from top to bottom, includes a strong adhesive layer with a thickness of 30-40 μm, a PET substrate layer, and a weak adhesive layer with a thickness of 15-25 μm.

[0043] The strong adhesive layer comprises the following components in parts by weight:

[0044] 100 parts of acrylic pressure-sensitive adhesive (Anzo Chemical Y-1420), 0.9 parts of epoxy crosslinking agent (Anzo Chemical EC-100 epoxy (1,3-bis(N,N-diglycidylaminomethyl)cyclohexane), 7 parts of rosin ester tackifying resin (Wuzhou Arakawa Rosin Resin GA-100), and 5 parts of toluene.

[0045] The weak adhesive layer comprises the following components:

[0046] The specific amounts of the following are listed in Table 1: portable acrylic pressure-sensitive adhesive, aziridine crosslinking agent (Anzo Chemical AZ-100 pentaerythritol tris(3-aziridine)propionate), isocyanate crosslinking agent (Covestro Desmodur L75 isocyanate aromatic TDI trimer), and toluene.

[0047] A method for preparing the above-mentioned easily disassembled PET strong and weak adhesive is also provided, comprising the following steps:

[0048] S1. Preparation of strong adhesive layer:

[0049] According to the above components and mass parts, at room temperature, add acrylic pressure-sensitive adhesive, toluene, tackifying resin and crosslinking agent to the container in sequence, set the mixer frequency to 15HZ and stir for 20 minutes until the tackifying resin is completely melted and stirred evenly to obtain a strong adhesive layer.

[0050] S2. Preparation of weak tack coat adhesive:

[0051] S21. Preparation of removable acrylic pressure-sensitive adhesive: In a reaction vessel equipped with a condenser, stirrer, and N2 protection, 100 parts of ethyl acetate, 5 parts of acrylic acid (AA), 70 parts of butyl acrylate (BA), 4 parts of hydroxyethyl acrylate (HEA), and 21 parts of methyl methacrylate (MMA) were added sequentially. The mixture was stirred and heated to 80°C. Simultaneously, 1 part of benzoyl peroxide initiator solution was added dropwise over a period of 3.0 h. After the addition was complete, the temperature was raised to 85°C and maintained for 1 h. The temperature was then lowered to 70°C, and 0.5 parts of 3,4-dihydroxyphenylalanine (DOPA) were added to continue the reaction for 1 h. The reaction was then stopped, and the pH was adjusted to 7 with ammonia to obtain the removable acrylic pressure-sensitive adhesive.

[0052] S22. According to the above components and mass parts, at room temperature, add the movable acrylic pressure-sensitive adhesive, toluene, aziridine crosslinking agent (Anzo Chemical AZ-100 pentaerythritol tris(3-aziridine)propionate), and isocyanate crosslinking agent (Covestro Desmodur L75 isocyanate (aromatic TDI trimer)) to the container in sequence. Set the mixer frequency to 15HZ and stir for 20 minutes. After stirring evenly, a weak adhesive layer is obtained.

[0053] S3. Preparation of easy-to-remove PET strong and weak adhesive tape:

[0054] A comma-shaped doctor blade coating method was used at a coating speed of 15 m / min to apply a strong adhesive layer to the double-sided release paper. After drying in an oven, it was bonded to one side of a 0.025 mm thick PET substrate. The dry adhesive layer thickness was 37 μm. After applying the strong adhesive layer and cleaning the coating machine, a weak adhesive layer was applied at a coating speed of 19 m / min onto the release film. After drying, it was bonded to the other side of the PET substrate. The dry adhesive layer thickness was 18 μm. The release film was then peeled off and wound up to obtain a 0.08 mm thick, easily detachable PET strong and weak adhesive tape. The drying temperature was adjusted according to the length of the coating machine oven, with the oven temperature set sequentially from low to high, ranging from a minimum of 50°C to a maximum of 120°C.

[0055] Table 1 Composition of the weak adhesive layer

[0056]

[0057] Example 2-3

[0058] The difference between this embodiment and Embodiment 1 is that the mass ratio of crosslinking agent A and crosslinking agent B in the components of the weak adhesive layer is different, as shown in Table 1. The rest is the same as in Embodiment 1.

[0059] Example 4

[0060] The difference between this embodiment and Embodiment 1 is that the total amount of crosslinking agent A and crosslinking agent B in the weak adhesive layer is different. The specific amounts are shown in Table 1. The rest is the same as in Embodiment 1.

[0061] Examples 5-6

[0062] The difference between this embodiment and embodiment 4 is that the mass ratio of crosslinking agent A and crosslinking agent B in the components of the weak adhesive layer is different, as shown in Table 1. The rest is the same as in embodiment 1.

[0063] Comparative Examples 1-2

[0064] The difference between this comparative example and Example 1 is that the mass ratio of crosslinking agent A and crosslinking agent B is different, as shown in Table 1. Everything else is the same as in Example 1.

[0065] II. Testing Methods

[0066] 1. 180° peel strength:

[0067] The PET strong and weak adhesive tapes prepared in the examples and comparative examples were cut into test samples with a width of 25 mm and a length of 200 mm. The surfaces of the PETG material plate and the nickel-plated stainless steel plate were thoroughly cleaned with alcohol and ensured to be completely dry. The strong adhesion side was attached to the PETG material plate and the weak adhesion side was attached to the nickel-plated stainless steel plate. The cut test samples and the adhesive layers to be tested were then attached to the cleaned plates. A 2 kg rubber roller was used to roll the tape back and forth three times at a speed of 300 mm / min to ensure that there were no air bubbles between the tape and the substrate. The tape was placed in an indoor environment with a temperature of 23℃±2℃ and a relative humidity of 50%±5% for 40 minutes. Then, a universal testing machine was used to perform a 180° tensile peel at a standard speed of 300 mm / min. The average peel force was recorded, which is the 180° peel strength, and the unit is gf / inch.

[0068] 2. Residual Adhesive: After the PET strong and weak adhesive tapes are completely peeled off the stainless steel plate, within 10 seconds, observe the surface of the stainless steel plate at different angles against the light to see if there are any dot-like, thread-like, or flaky residues. Then, gently run your clean index finger over the test area to observe if there is any sticky feeling.

[0069] 3. Environmental stability: The PET strong and weak adhesive tapes prepared in the examples and comparative examples were cut into test samples with a width of 25 mm and a length of 200 mm. The constant temperature and humidity chamber was set at 70℃ and 85%RH. The test samples were placed in the constant temperature and humidity chamber for aging for 8 hours. After aging, the test samples were taken out and placed in a standard environment (23℃, 50%RH) for 1 hour for condition adjustment. Then, the 180° peel strength test was immediately performed and the presence of residual adhesive in the weak adhesive layer and the presence of excess adhesive or residual adhesive in the strong adhesive layer were observed.

[0070] After testing and observation, the adhesive tapes prepared in Examples 1-6 showed no excess adhesive or residual adhesive in the strong adhesive layer after the thermal aging test. Other test results are shown in Table 2.

[0071] Table 2 Test results of the tape

[0072]

[0073] As shown in Table 2, in the preparation of PET strong and weak adhesive tapes in Examples 1-6, the total amount of crosslinking agent A and crosslinking agent B in the weak adhesive layer component is 0.8-1.2 parts, and the mass ratio of crosslinking agent A to crosslinking agent B is (1-3):1. The prepared tape weak adhesive layer achieves a balance in terms of interfacial adhesion, heat resistance of adhesive, and no adhesive residue.

[0074] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0076] The present invention has been illustrated with the above embodiments to describe the detailed process flow of the present invention. However, the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A strong and weak adhesive that is easy to disassemble, characterized in that, From top to bottom, it includes a strong adhesive layer with a thickness of 30-40μm, a substrate layer, and a weak adhesive layer with a thickness of 15-25μm.

2. The adhesive for easy disassembly and bonding of strong and weak bonds as described in claim 1, characterized in that, The strong adhesive layer comprises the following components in parts by weight: 100 parts acrylic pressure-sensitive adhesive, 0.8-1.0 parts crosslinking agent, 3.0-10.0 parts tackifying resin, and 5.0-7.0 parts solvent.

3. The adhesive for easy disassembly and bonding of strong and weak bonds as described in claim 2, characterized in that, The crosslinking agent is selected from isocyanate or epoxy crosslinking agents.

4. The adhesive for easy disassembly and bonding of strong and weak bonds as described in claim 2, characterized in that, The tackifying resin is selected from rosin esters or terpene resins.

5. The adhesive for easy disassembly and bonding of strong and weak bonds as described in claim 2, characterized in that, The solvent is selected from at least one of toluene, ethyl acetate, and butanone.

6. The adhesive for easy disassembly and bonding of strong and weak bonds as described in claim 1, characterized in that, The substrate layer is selected from any one of polyethylene terephthalate (PET), polyethylene (PE) foam substrate, and thermoplastic polyurethane elastomer (TPU).

7. The adhesive for easy disassembly and bonding of strong and weak bonds as described in claim 1, characterized in that, The weak adhesive layer comprises the following components in parts by weight: 100 parts of portable acrylic pressure-sensitive adhesive, crosslinking agent A, crosslinking agent B, and solvent 10-12 parts.

8. The adhesive for easy disassembly and bonding of strong and weak bonds as described in claim 7, characterized in that, Crosslinking agent A is an aziridine-type crosslinking agent, and crosslinking agent B is an isocyanate-type crosslinking agent.

9. The adhesive for easy disassembly and bonding of strong and weak bonds as described in claim 8, characterized in that, The total amount of crosslinking agent A and crosslinking agent B is 0.8-1.2 parts; the mass ratio of crosslinking agent A to crosslinking agent B is 1-3:

1.

10. A method for preparing the easily disassembled strong and weak adhesive according to any one of claims 1-9, characterized in that, The process involves weighing and mixing the components of the strong adhesive layer according to their mass ratio to obtain a strong adhesive layer adhesive, weighing and mixing the components of the weak adhesive layer according to their mass ratio to obtain a weak adhesive layer adhesive, applying the strong adhesive layer adhesive to the surface of a release material, drying it, and then bonding it to one side of a substrate, and applying the weak adhesive layer adhesive to the surface of the release material, drying it, and then bonding it to the other side of the substrate to obtain an easily removable strong-weak adhesive.

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